Computers .. These "creatures" appeared on our planet relatively recently, and for many years they have been gathering thousands of people around them, attracting with their capabilities. Someone plays computer games, someone writes articles on them, and sometimes they can serve as your second TV or information keeper. When using your computer, have you ever asked yourself the question, "How the hell does this work?" Even if they asked, they probably did not answer it, surfing the Internet and wasting hours of their time. Actually, that's why I'm here. I will tell you in a nutshell what exactly is in your computer and how it works.
Part 6. Network card
Probably, if it were not for the current trend of getting all the information on the Internet, as well as using it to communicate and play games together (and a thousand other possibilities, to be honest), I would not have mentioned the network card. But the Internet has now captured almost the entire planet, and now no computer can do without a network card. That is why I am simply obliged to remind you of the existence of such a card as a network card.
Are you using a laptop? Then this article is just for your reference, because now a network card is built into all motherboards for laptops. And not only in order to connect the patch cord (a wire consisting of 8 multi-colored fibers. It also has a latch), but also in order to be able to connect to the wireless Internet. Like the two previous cards, the network card looks like a small piece of the motherboard crammed with the same microcircuits.
The network card is very similar to the human mouth: it is the mouth that allows us to communicate with other people, and for this we do not have to connect to the interlocutor with any wire. For how many channels are inside. It is with the help of a network card that you can connect to the router using a wire, and if the card has a wireless adapter, then you can connect without a wire.
Let's imagine that your motherboard has no network card integrated. All the same, anything can be, and it will not hurt for general development.
What does a network card consist of?
1. Processor or chip. There is a processor in the network card only if the card is needed for a server, not a stationary computer. Alas, unlike sound and video cards, ordinary network cards do not have their own processor, and therefore they turn to the central processor, and that in turn does its job: it transfers frames from the computer's RAM to the network. And in the opposite direction too.
2. RJ-45 connector. Designed for a patch cord that can come both from a workgroup switch (a piece that unites all computers in one office of some large company, for example), and from a router (in very small networks, like my home).
3. Slot for BootRom. There are not always. What is it? You know, sometimes information in some companies is so confidential and protected that ordinary computers simply do not supply hard drives. BootRom, in turn, is such a thing that helps to connect to the server's hard drive and allow a regular computer to work with it. After all, this microcircuit has a code in it that allows you to connect to the network even without a hard drive.
Buying a network card
Strictly speaking, the purchase of a network card is justified by only one nuance: if the motherboard is covered, then everything that is built into it will be covered. Having spent one time on separate equipment, on all the boards that I listed, you will reduce costs in the distant future. It is important.
1. Manufacturer. Look at it first, since the characteristics of the cards are always very similar, and it simply won't work to choose hardware based on one or several numbers. Good manufacturers include D-Link, TP-Link and Cisco. It is quite possible to experiment and buy products from other manufacturers, but do it at your own peril and risk.
2. Data transfer rate. Although the characteristics are almost the same everywhere (10/100 Mbps), sometimes the card is designed for really fast work. In this case, its transmission speed will be 10/100/1000 Mbps. Only in this case you will have to use a category 5e patch cord, no less.
3. BootROM port. You don't need it unless you are a member of a well-secured corporate network. And if you are, then the computer will be given to you already assembled, and this component will be there.
Actually, there is nothing more to watch. Honestly, the question of choosing a network card is entirely up to your aesthetic pleasure. It would be most correct to choose the right manufacturer, and the rest will come by itself. Moreover, the speed of the Internet, first of all, does not depend on the network card, but on the provider that supplies you with the Internet.
In small, home networks, try to install exactly the network card that allows you to connect to wireless Internet, and calmly run Wi-Fi around the house. For laptops that don't have a wireless internet connection, you can buy a small USB adapter that costs no more than 1,000 rubles.
Stay tuned for updates on the site and read more about computers and their little secrets.
26. 03.2017
Dmitry Vassiyarov's blog.
Network card or network adapter what is it?
Hello dear visitors.
Today we'll talk about the next piece of hardware, and more specifically about what a network card is. Do you work in an enterprise where there is a corporate connection between computers? Then you should learn more about the network adapter, since it is he who serves as a link between office computers.
Getting to know better
Not with me, but with a network card, of course :).
In English, it is called "network interface controller / card" (NIC), that is, "network interface controller or card". Also, according to the technology used in the operation of the device, it has another name - Ethernet adapter.
So that you understand its essence, I will decipher the first word: "ether" is translated as "ether", and network - "network, chain". The concept itself means a family of technologies for packet transmission of information among computer networks.
The network card is designed to create local networks between computers and / or their connection to the Internet. In other words, you cannot connect to the Internet without it.
Recently, communication has been organized using a special cable - an eight-core twisted pair, equipped with an "8P8C" connector, that is, it has 8 conductors in the same number of places for them.
Connect such a pair to a modern network and a new model card, and you will get speeds from 100 Mbps to 1 Gbps (Gigabit). That is, if, of course, your provider gives you this speed.
This technology is called Gigabit Ethernet and is relatively popular now. Its main competitors include fiber optic, Docsis (connecting computers using a TV cable) and DSL technology (using a telephone cable).
Also, the connection can be made using the 15-pin AUI connectors of the transceiver for a thick coaxial cable or a BNC connector for the same cable, only a thin one.
Types of network cards
The main criterion for distinguishing Ethernet adapters is their way of connecting to a computer:
Main settings
Considering buying a network card? Consider when choosing not only the types of cables and the interface, but also the following characteristics:
- Bit depth (bus bandwidth). It comes in 8, 16, 32 and 64 bits. In ordinary computers, as a rule, a 32-bit device is installed, and in server computers, the maximum volume. Do you have a very old computer and operating system? Then it might be worth looking into 16 or even 8-bit boards.
- Controller microcircuit (chip). The most reliable are third-generation adapters based on integrated circuits (ASICs). High-quality chipsets are now being produced by the brands realtek, intel, broadcom, etc.
- Data transfer rate. It starts at 10 Mbps and can go up to 100 Gbps. But don't chase the highest rate. Since not all providers will be able to give you the maximum speed. Or rather, there may not be any at all.
What card is on your computer?
Can't you answer this question? Then we will find out now. We go along the path Start - Control Panel - Device Manager (in case you have Windows). You can find it in the System and Security - System menu. Find the one you need among the devices on your computer.
In principle, I think I wrote everything in detail.
You now have a basic knowledge of what a network card is.
Come back to me for more information.
See you soon and don't forget to subscribe for updates.
Not sure which network card is used on your computer? No problem! In order to find out, you don't even need to install third-party programs. Everything can be done using the built-in Windows tools.
How to find out the model of a network card through the Device Manager
The easiest way to find out which network card is on your computer is to use a tool called "Device Manager". In order to open the "Device Manager" go to the Control Panel, and then go to the "System and Security - System" section. Here, in the left sidebar, there will be a link to Device Manager.
Alternatively, you can open Device Manager with the command "mmc devmgmt.msc". To do this, press the key combination Windows + R , in the window that appears, enter "mmc devmgmt.msc" and press the enter key.
Well, Windows 8 and Windows 10 users can open the "Device Manager" by right-clicking on the "Start" button.
After opening the "Device Manager", you need to open the "Network adapters" section. There you can see which network card is on your computer. In our case, this is the integrated network card Qualcomm Atheros AR8152 PCI-E Fast Ethernet Controller.
It should be noted that the "Network adapters" section can display virtual network cards created by various programs. But, they are easy to distinguish from real network cards, since they are named by analogy with the programs that create them. In our screenshot (at the top), such a virtual network card is the Virtual Box Host Only Ethernet Adapter.
Using the command line to get information about network cards
The second way to find out which network card is on the computer is through the command line. To use this method, open the start menu and enter the command "CMD" in the search. Thus, you must open a Windows command prompt. In the command line that opens, enter the command "IPCONFIG / ALL" (screenshot below).
After executing this command, the command line will display information about all network connections on your computer. For each of these connections, the Description section will indicate the name of the network card that is responsible for this connection.
How to find out which network card I have using the msinfo32 command
Another option for obtaining information about a network card is the "msinfo32" command, which opens a tool called "System Information". To use this tool, press the key combination Windows + R and in the window that appears, enter the command "msinfo32".
It is impossible to connect to the Internet if the computer does not have a network adapter into which a cable is installed, led to the room by the provider. That is why almost every motherboard has a built-in adapter. But if it is missing or out of order, it becomes necessary to install a network card. You can find out how to do this in our guide.
Adapter check
If you set up a Netgear WNR612V2 router or any other router, you must have seen a network card port (RJ-45) on the back of the system unit. It looks like this: 
If the connector is near other ports (usually USB) - you are dealing with an integrated network card. 
If the RJ-45 port is located separately from other connectors, then your system unit has a separate card that is responsible for connecting to the network.
After detecting the port, you need to verify that the hardware is installed correctly in the system.
To do this, go to the "Device Manager" and make sure that the network card is detected, and its drivers are installed correctly. 
Reinstall them if necessary.
The network adapter can also be disabled in the BIOS. Reboot your computer and enter the basic I / O system.
Find the PCI Confuguration option (usually found under the Advanced section) Check that LAN Controller is set to Enabled. 
Connection
If you do not find the connector you need on the back of the system unit, you will have to connect your network card.
Important! Please make sure your motherboard has the correct slot for installing the board before purchasing.
Usually cards are produced with PCI interface, but there are also models that support PCI-E technology. They are not interchangeable, so if the interface is incorrectly selected, you will not be able to connect the equipment. 
A universal option is a USB card that will fit any computer. 
The procedure for installing a network card is no different from connecting a video card to a computer:
After the system starts up, a message about new hardware found will appear on the screen. You just have to install the drivers so that the device works correctly.
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Network boardAlso known as a network interface card, network adapter, Ethernet adapter, NIC (English network interface card) is a peripheral device that allows a computer to communicate with other devices on a network. Nowadays, especially in personal computers, network cards are quite often integrated into motherboards for convenience and reduce the cost of the entire computer as a whole.
Types
By constructive implementation, network cards are divided into:
- internal - separate cards inserted into the ISA, PCI or PCI-E slot;
- external, connected via USB or PCMCIA interface, mainly used in laptops;
- * built into the motherboard.
On 10-Mbps network cards, 3 types of connectors are used to connect to a local network:
- 8P8C for twisted pair;
- BNC connector for thin coaxial cable;
- 15-pin AUI transceiver connector for thick coaxial cable.
- optical connector (en: 10BASE-FL and other 10 Mbit Ethernet standards)
On 100-Mbps boards, either a twisted pair connector (8P8C, mistakenly called RJ-45, or an optical connector (SC, ST, MIC)) is installed.
One or more information LEDs are installed next to the twisted pair connector, indicating the presence of a connection and information transfer.
One of the first mainstream network cards was the Novell NE1000 / NE2000 series with a BNC connector.
Network adapter parameters
When configuring the NIC card, the following options may be available:
- hardware interrupt request line number IRQ
- dMA channel number (if supported)
- base I / O address
- base address of RAM memory (if used)
- support for auto-negotiation duplex / half-duplex standards, speed
- support for tagged VLAN packets (802.1q) with the ability to filter packets of a given VLAN ID
- wOL (Wake-on-LAN) parameters
- auto-MDI / MDI-X function automatic selection of the mode of operation for straight or cross-crimped twisted pair
Depending on the power and complexity of the network card, it can implement computational functions (mainly counting and generating checksums of frames) in hardware or software (by a driver of a network card using a central processor).
Server NICs can be supplied with two (or more) NICs. Some network cards (built into the motherboard) also provide firewall functionality (such as nforce).
Functions and characteristics of network adapters
A network adapter (Network Interface Card (or Controller), NIC), together with its driver, implements the second, link layer of the open systems model at the end node of the network - the computer. More precisely, in a network operating system, the adapter and driver pair performs only the functions of the physical and MAC layers, while the LLC layer is usually implemented by the operating system module, which is the same for all drivers and network adapters. Actually, this is how it should be in accordance with the model of the IEEE 802 protocol stack. For example, in Windows NT the LLC level is implemented in the NDIS module, which is common to all network adapter drivers, regardless of which technology the driver supports.
The network adapter together with the driver perform two operations: frame transmission and reception. The transfer of a frame from a computer to a cable consists of the following steps (some may be missing, depending on the accepted encoding methods):
- Formatting the MAC layer data frame in which the LLC frame is encapsulated (with flags 01111110 discarded). Filling in the destination and source addresses, calculating the checksum. Receiving the LLC data frame via the interlayer interface along with the MAC layer address information. Typically, communication between protocols inside a computer occurs through buffers located in RAM. Data for transmission to the network is placed in these buffers by upper-layer protocols, which retrieve it from disk memory or from the file cache using the I / O subsystem of the operating system.
- Formation of code symbols when using redundant codes of type 4B / 5B. Scramble codes to obtain a more uniform signal spectrum. This step is not used in all protocols - for example, 10 Mbps Ethernet technology does without it.
- Outputting signals to the cable in accordance with the accepted line code - Manchester, NRZ1. MLT-3, etc.
- Isolation of signals against the background of noise. This operation can be performed by various specialized microcircuits or DSP signal processors. As a result, a certain bit sequence is formed in the adapter receiver, which with a high degree of probability coincides with the one sent by the transmitter.
- If the data was scrambled before being sent to the cable, then it is passed through the descrambler, after which the code symbols sent by the transmitter are restored in the adapter.
- Frame checksum check. If it is incorrect, then the frame is discarded, and the corresponding error code is transmitted to the LLC protocol through the interlayer interface upward. If the checksum is correct, then the LLC frame is extracted from the MAC frame and transmitted through the interlayer interface upward, to the LLC protocol. The LLC frame is placed in the RAM buffer.
The distribution of responsibilities between the network adapter and its driver is not defined by standards, so each manufacturer decides this issue independently. Typically, network adapters are divided into adapters for client computers and adapters for servers.
With adapters for client computers, much of the work is offloaded to the driver, making the adapter simpler and cheaper. The disadvantage of this approach is the high degree of loading of the computer's central processor with routine work on transferring frames from the computer's RAM to the network. The central processor is forced to do this work instead of performing user application tasks.
Therefore, adapters designed for servers are usually equipped with their own processors, which independently perform most of the work of transferring frames from RAM to the network and vice versa. An example of such an adapter is the SMC EtherPower NIC with an embedded Intel i960 processor.
Depending on what protocol the adapter implements, adapters are divided into Ethernet adapters, Token Ring adapters, FDDI adapters, etc. Since the Fast Ethernet protocol allows, through the auto-negotiation procedure, to automatically select the speed of the network adapter depending on the capabilities hub, many Ethernet adapters today support two speeds and have a 10/100 prefix in their name. Some manufacturers call this property autosensitivity.
The network adapter must be configured before being installed in a computer. Configuring an adapter typically specifies the IRQ number used by the adapter, the DMA channel number (if the adapter supports DMA mode), and the base address of the I / O ports.
If the network adapter, computer hardware, and operating system support Plug-and-Play, the adapter and its driver are automatically configured. Otherwise, you must first configure the network adapter and then repeat its configuration parameters for the driver. In general, the details of the procedure for configuring a network adapter and its driver largely depend on the manufacturer of the adapter, as well as on the capabilities of the bus for which the adapter is designed.
Classification of network adapters
As an example of the classification of adapters, we use the approach of 3Com. 3Com believes that Ethernet network adapters have gone through three generations.
First generation
Adapters first generation were executed on discrete logic microcircuits, as a result of which they had low reliability. They had a buffer memory for only one frame, which led to poor performance of the adapter, since all frames were transferred from computer to network or from network to computer sequentially. In addition, the first generation adapter was configured manually using jumpers. A different driver was used for each type of adapter, and the interface between the driver and the network operating system was not standardized.
Second generation
In network adapters second generation to improve performance, the multi-frame buffering method was used. In this case, the next frame is loaded from the computer memory into the adapter buffer simultaneously with the transmission of the previous frame to the network. In the receive mode, after the adapter has completely received one frame, it can start transmitting this frame from the buffer to the computer memory at the same time as receiving another frame from the network.
Second-generation network adapters widely use highly integrated microcircuits, which improves adapter reliability. In addition, the drivers for these adapters are based on standard specifications. Second-generation adapters typically come with drivers that operate in both the NDIS (Network Driver Interface Specification), developed by 3Com and Microsoft and approved by IBM, and the ODI (Open Driver Interface), developed by Novell.
Third generation
In network adapters third generation (among them 3Com refers to its adapters of the EtherLink III family) is a pipelined frame processing scheme. It lies in the fact that the processes of receiving a frame from the computer's RAM and transmitting it to the network are combined in time. Thus, after receiving the first few bytes of the frame, their transmission begins. This significantly (by 25-55%) increases the performance of the "RAM - adapter - physical channel - adapter - RAM" chain. This scheme is very sensitive to the start of transmission threshold, that is, to the number of frame bytes that are loaded into the adapter buffer before starting transmission to the network. The third generation network adapter performs self-tuning of this parameter by analyzing the working environment, as well as by calculation, without the participation of the network administrator. Self-tuning provides the best possible performance for a particular combination of performance on the computer's internal bus, interrupt, and DMA.Third-generation adapters are based on Application-Specific Integrated Circuits (ASICs), which improve adapter performance and reliability while reducing cost. 3Com has named its pipelining technology Parallel Tasking, and other companies have implemented similar designs in their adapters. Improving adapter-to-memory link performance is critical to improving overall network performance, since the performance of a complex frame path, such as hubs, switches, routers, WANs, and so on, is always determined by the performance of the slowest element of this route. Therefore, if the network adapter of the server or client computer is slow, no fast switches will be able to improve the speed of the network.
Today's network adapters can be classified as fourth generation... These adapters necessarily include an ASIC that performs the functions of the MAC-level (English MAC-PHY), the speed is developed up to 1 Gbit / s, as well as a large number of high-level functions. The set of such functions may include support for the RMON remote monitoring agent, frame prioritization scheme, functions for remote computer control, etc. Server versions of adapters almost necessarily have a powerful processor that offloads the central processor. An example of a Gen 4 network adapter is the 3Com Fast EtherLink XL 10/100 adapter.
